While I had only collider meshes and some lowpoly templates it was so easy and fast to use ctrl+s and jump to unity and everything was updated in a second.

In modo it's possible to make references of items from other file, haven't used it, but I think it could be useful for this. Edit the scene with all meshes and make other scene that has references/instances of lowpoly meshes. When needed export/save scene with lowpoly meshes